1. Field of the Invention
The invention relates to cosmetic or dermatological preparations comprising potassium sorbate as preservative and microcrystalline cellulose and/or talc and/or, on the basis of W/O or W/S emulsions, non- or mid-polar lipids as stabilizing agents.
2. Discussion of Background Information
The antimicrobial effect of sorbic acid has been known since 1939. The derivatives of sorbic acid used are primarily the alkali metal salts as preservatives, especially in the food sector. The particular advantage of the alkali metal sorbates is their good solubility in water. Sorbic acid and their potassium and/or sodium salt are recommended as preservatives, mostly in amounts of 0.05-0.2% by weight, for pharmaceutical and cosmetic preparations (E. & P. Pelle, Gyogyszzereszet 15, 94 [1971] [hun]; C.A. 75, 52752 [1971]). As known from diverse investigations, in contrast to other preservatives, sorbic acid and the alkali metal sorbates behave extremely favorably with regard to the toxicological properties. Neither sorbic acid nor potassium sorbate are carcinogenic, mutagenic or teratogenic.
Since sorbic acid and the alkali metal sorbates are used as preservatives for cosmetics, their tolerability by the skin has also been studied and no negative properties at all have been found. The properties of sorbic acid and/or of potassium sorbate, which is preferably suitable for preserving cosmetic compositions which have been rendered acidic, can be found, for example, in E. Lück & K. Remmert, SÖFW 118, 699 [1992]. The World Health Organisation has documented the acceptability of sorbic acid and/or alkali metal sorbates by the fact that it has fixed for these substances the highest value of the acceptable daily dose for preservatives, i.e., 25 mg/kg of body weight.
Due to the physiological acceptability, sorbic acid and alkali metal sorbates are used in preserving articles which come into contact with human or animal skin during production, processing or use.
It is known that in cosmetics potassium sorbate degrades and leaves behind a very unpleasant odour which can be detected even in trace amounts. The oxidative degradation products can also lead to discoloration problems, meaning that potassium sorbate cannot be used in cosmetics on its own or with the customary preservatives. It is known to add stabilizers such as allantoin or BHT to the preparation to avoid these unacceptable aspects of cosmetics which contain potassium sorbate. BHT is a synthetically prepared antioxidant and preservative. BHT, being a toluene derivative, is not regarded as being completely uncritical in toxicological terms, and is used in cosmetics only in exceptional cases. In particular, BHT should not be used in cosmetics for people with allergies.
Allantoin is a skin-smoothing active ingredient with only a low stabilizing potential, rendering it unsuitable for use as a stabilizing agent for preservatives.
It would be desirable to have available a cosmetic or dermatological composition which comprises potassium sorbate as preservative and nevertheless does not have the disadvantages of the potassium sorbate containing preparations known from the prior art. In particular, it would be advantageous to have available a composition which comprises only small amounts of preservative and added stabilizers.